I'm using Racket with Geiser and I get this error: executing Scheme code block... => #f org-babel-scheme-execute-with-geiser: Invalid read syntax: "#" when in an org-mode file this code #+begin_src scheme :exports both :session ch3 (define (bool-imply2 x y) (or (not x) y)) #+end_src is run (C-c-c) #+BEGIN_SRC scheme :session ch3 (bool-imply2 #t #f) #+END_SRC In the Racket "ch3" REPL session (bool-imply2 #t #f) works fine. I discovered this problem when I first tried a simple export to HTML of the buffer. It seems to not like the second boolean parameter. So switching the parameters then complains about #t . What might be going on? BTW, does an export try to "run" all the code blocks, i.e., why did I find this when I was exporting to HTML? LB